The present invention relates to a semiconductor package for receiving a CCD (Charge Coupled Device), ROM (Read Only Memory) or similar semiconductor device and sealing it therein with a cap adhered thereto. More particularly, the present invention relates to a semiconductor package with improved air-tightness and close adhesion to a cap.
A semiconductor package of the kind described is disclosed in, for example, Japanese Patent Laid-Open Publication No. 2-7453. The conventional package has an upper surface to which a cap is to be adhered. A plurality or grooves are formed in the upper surface of the package. When the cap is adhered to and pressed against the package, air inside the package is forced out and replaced with nitrogen via the grooves. Such a configuration, however, lacks an implementation for guiding the cap on the upper surface of the package and, therefore, obstructs the accurate positioning of the former on the latter.
In light of the above, there has been proposed a semiconductor package having a stepped recess in the upper surface thereof. The stepped recess forms side walls which play the role of guide means when a cap is received in the recess, so that the cap may be accurately positioned on the package. This kind of scheme, however, brings about another drawback that the side walls, or guide means, prevent air inside the package from being fully discharged in the event of adhesion of the cap to the package. As a result, not only the sealability of the package but also the close adhesion thereof to the cap are degraded.